Tract integrity predicts neurological outcomes in neonatal hypoxic-ischemic encephalopathy.

Objective: Early prognostication in infants with neonatal hypoxic-ischemic encephalopathy (HIE) is crucial for follow-up management. Alternations of microstructural integrity of neural fiber tracts in large-scale neural networks might predict neurological outcomes.

Methods: All consecutively-admitted patients with neonatal HIE from 2016 to 2020 were enrolled. Diffusion tensor imaging (DTI) tractography was performed at 4-7 days of age. Neurodevelopmental outcomes at 24 months of age were assessed with Bayley Scales of Infant Development, 3rd edition.

Results: A total of 62 HIE infants were enrolled, and 53 of these underwent DTI. Fractional anisotropy (FA) and mean diffusivity (MD) were measured to indicate the microstructural integrity of tracts, including the arcuate fasciculus, uncinate fasciculus, inferior fronto-occipital fasciculus, corticospinal tract (CST), and optic radiations (OR). Lower FA values of target tracts were associated with lower developmental scores at 24 months of age, particularly in the CST and OR (all P ≤ 0.003). The prognostic accuracy of FA values in CST surpassed that in the region of thalamus/basal ganglia (area under curves 0.839, 95 % CI: 0.728-0.950 vs. 0.755, 95 % CI: 0.583-0.928). Furthermore, the correlation between FA values in target tracts and developmental scores was most significant in infants with HIE stage III and this was not affected by therapeutic hypothermia.

Conclusion: Tract integrity in the CST and OR detected by DTI provides valuable insights for early prognostication in infants with HIE, regardless of therapeutic hypothermia.